The present invention relates to a system for controlling the operation of an automotive engine, and more particularly to a learning control system for updating data stored in a table for the learning control. In the learning control syste, the updating of data is performed with new data obtained during the steady state of engine operation. Accordingly, means for determining whether the engine operation is in steady state is necessary. A conventional learning control system has a matrix (two-dimensional lattice) comprising a plurality of divisions, each representing engine operating variables such as engine speed and engine load. When the variables continue for a predetermined period of time in one of the divisions, it is determined that the engine is in steady state. On the other hand, a three-dimensional look-up table is provided, in which a matrix coincides with the matrix for determining steady state. For such a three-dimensional table, a RAM having a large capacity must be provided.
In order to reduce the capacity of the RAM, in a fuel injection control system, a two-dimensional look-up table dependent on one of variables, such as engine load, is provided regardless of engine speed. However, at low engine load under particular conditons such as a traffic jam, the air-fuel ratio of the air-fuel mixture should be controlled taking also engine speed into consideration in order to provide a proper air-fuel ratio.